Air flow control for refrigerators



Dec. 6, 1955 s. v. SWANSON AIR FLOW CONTROL FOR REFRIGERATORS Filed Jan. 14, 1952 n w WWW/M 2 i if [nuenTor SvenV. womso mm MW Affovne United States Patent AIR FLOW CONTROL FOR REFRIGERATORS Sven V. Swanson, Niles, Mich., assiguor to Tyler Refrigeration Corporation, a corporation of Michigan Application January 14, 1952, Serial No. 266,411

6 Claims. (Cl. 62-895) This invention relates to a novel arrangement of vanes or louvers for the control of air flow in open refrigerated cases and the method of accomplishing the result. This invention is particularly adapted for use with open top or reach in cases used for the display and dispensing of refrigerated foods in grocery stores and meat markets. The temperature of the foods is kept at near freezing to below 0 F. depending on the product, while the atmospheric temperature of the room may be quite high.

In this type of case it is desirable to keep the mixing of room air and the refrigerator air in the display area to a minimum. Still there must be a considerable quantity of refrigerated air moving through the display area in order to absorb the heat leaking into this area due to transfer through the walls and, to a great extent, due to radiant heat and water vapor entering from the surrounding air. Too

small a quantity of moving air results in warm merchandise, because radiant heat impinging is absorbed by the merchandise and water vapor diffuses from the room air into the refrigerated space faster than it is removed by the refrigerated air.

To obtain efficient refrigeration with minimum mixing, the air outlet louvers as shown in the accompanying drawing were devised. These louvers give a thin air stream over the display area. The louvers are so arranged that the velocity near the merchandise is greater than the velocity at the top of the air stream. The lower velocity at the top of the air stream where mixing with the room air takes place, considerably reduces the turbulence in this area. With less turbulence there is less mixing which in turn reduces the refrigeration loss thus increasing the efiiciency of the apparatus.

The invention is hereafter more fully described and particularly pointed out in the claims, reference being had to the accompanying drawings in which:

Fig. l is a diagrammatic style sectional elevation of a refrigerator showing the essential features of the invention, and

Fig. 2 is a like diagrammatic sectional elevation of the upper rear portion of the refrigerator showing a modified form of air directing louvers or vanes.

Like reference characters refer to like parts in both of the figures.

1 represents generally the exterior construction of the refrigerator casing which is suitably insulated against heat transfer. The casing has an open top through which the goods in the merchandise container 2 are visible and accessible for removal. The container 2 is located within the casing 1 and its top is considerably below the top of the casing. The front 3 of the container is spaced from the front 4 of the casing providing a substantially vertical passage 5 for the downward flow of an air current.

The bottom 6 of the container 2 is spaced above the bottom of the casing providing a space constituting an air passage and in which are located a motor driven fan 7, a refrigerating element R, such as the evaporator of a refrigerating apparatus, and a plenum chamber 8. The back 9 of the container 2 is spaced from the back 10 of the 2,725,726 Patented Dec. 6, 1955 "ice casing forming a passage 11 for an upward current of air and in which is located a metering orifice 12.

The object of the metering orifice 12 is to restrict the flow of air from the plenum chamber 8 causing a slight pressure of air in said plenum chamber. This plenum in the chamber 8 will back up into the refrigerating element R and will cause the air pressure to be evenly distributed throughout the length of the cabinet fully utilizing the capacity of the refrigerating element and causing an even flow throughout the length of the outlet passage 11.

The back 10 of the casing extends upwardly above the back of the container and is provided with a forwardly extending hood 13 which projects over the rear of the container 2. In the space between the upper edge of the back 9 of the container and the hood 13 are located a plurality of air directing vanes generally indicated as 15. The rear edges of these vanes are located above the air passage 11 and in the path of an upward air current therefrom and their forward edges are located above the rear of the container 2. The sectional views of Figs. 1 and 2 are what may be called front to rear sections and the refrigerator and vanes 15 have considerable length in a direction transverse to these sections.

An air current, induced by the fan 7, is discharged into the plenum chamber 8. The static pressure built up in this chamber causes the air to flow with considerable velocity past and/or through the refrigerating element R where it is cooled and from where it enters the plenum chamber 8. From the plenum chamber 8 the air escapes through the orifice 12 and passes upward in a rapid stream through the passage 11, from where it emerges against the deflector vanes 15 which change its course and direct it forwardly over the merchandise container 2 to the front of the case from where it flows downwardly again into the vicinity of the fan 7. l

The purpose of the deflector vanes 15 is to both change the direction of the air current and to stratify it causing a plurality of horizontal strata, each having a different velocity, to flow over the merchandise, the velocity of each respective stratum increasing from top to bottom.

The exact shapes of the vanes 15 may be varied to some extent so long as they produce the result of stratifying the air into horizontal superimposed layers of different velocity, the more rapid at the bottom and the slower at the top. The vanes of Fig. 1 are of arcuate cross section and those of Fig. 2 have vertical rear portions merging into horizontal tops with downwardly inclined forward portions. Both of these forms, as well as other modifications will give the desired results in varying degrees. For a given volume of air the form shown in Fig. 1 gives a lower outlet velocity than that of Fig. 2. It also occupies more vertical height and in general would be used for lower temperature applications.

In both forms of vanes shown the respective rear edges of the vanes of each series are arranged in the upflowing air stream from the passage 11, both horizontally and vertically, so that they will respectively, from bottom to top, deflect a slower moving stratum of air and direct it forwardly, and downwardly to some extent, over the merchandise in the container 2. The downward direction of the current is caused largely by gravity because the air is very much colder than the surrounding atmosphere and has a natural tendency to fall.

The result of this structure in its operation is to cause a relatively thin stream of refrigerated airin stratified form to flow from rear to front over the merchandise on display, the respective strata from bottom to top moving with decreasing speed. Of course the velocity of each stratum gradually diminishes after it leaves the deflecting vanes 15, and it is probable that the upper stratum or some of the upper strata will cease flowing before it reaches the front of the case, but throughout its movement each stratum protects that below it. The slower moving upper strata create small turbulence upon contact with the surrounding atmosphere and as a next lower stratum outreaches an upper stratum its speed will have diminished so that it will cause small turbulence in the surrounding air.

Thus the lower and more rapidly moving strata of air currents are protected by those above against contact or intermixing with the warm surrounding atmosphere which would raise their temperature and slow their speed and the lower layers of air current are enabled to pass completely over the merchandise from rear to front with relatively low temperature change resulting in a complete blanket of cold air over the entire merchandise display at all times.

It is true that some of the cold air from the lower stratum will fall by gravity into the container 2, but the amount of air thus descending is relatively small and does not detract from the air flow sufiiciently to prevent its reaching the front of the container and maintaining a complete blanket over the goods.

The air in the upper slower moving strata which becomes lost or merges with the surrounding air is com pensated for by a like quantity of the surrounding air entering the passage at the front of the case, but since this warm admixture of air is passed through the cooling element R before passing over the merchandise, it does not interfere with the refrigerating process.

The invention is defined by the appended claims and is to be considered as comprehensive of all forms coming within their scope.

I claim:

1. The method of refrigerating articles in an open topped case consisting of blowing a stratified stream of refrigerated air over said case from one side to the other, said stratified air stream consisting of a plurality of substantially horizontal layers each moving with different velocity, the lower layer moving with greatest velocity and 4 the respective upper layers moving with progressively slower velocity.

2. The method defined by claim 1 in which said upper slower moving air layers have insufficient force to pass entirely across said case.

3. The method defined by claim 1 in which each slower moving layer shields the next lower layer against contact with the surrounding atmosphere.

4. The method defined by claim 1 in which said stratified layers are closely contiguous preventing interspersion of dead air between them.

5. A refrigerator of the class described comprising, a casing having an open top, an open topped article container within said casing, an air passage within said casing having an inlet at one side of said container and an outlet at the other side of the container, means for creating a current of air and for refrigerating said air in said passage, and means at said outlet for stratifying said air current into a plurality of layers of different velocity and for directing said Stratified current across the open top of said container toward said inlet, with said faster moving layers underlying the slower moving layer.

6. The elements of claim 5 combined with a metering orifice at the outlet side of said air passage acting to create a plenum in said air passage whereby the flow of air therefrom is evenly distributed.

References Cited in the file of this patent UNITED STATES PATENTS 1,961,948 Symonds June 5, 1934 2,050,063 Millott Aug. 4, 1936 2,243,958 Hermann June 3, 1941 2,255,616 Heasley Sept. 9, 1941 2,421,314 Brinkoeter May 27, 1947 2,466,286 Stultz Apr. 5, 1949 2,506,977 Tortorelli May 9, 1950 FOREIGN PATENTS 584,678 Great Britain Jan. 21, 1947 

